Problem: What do the following two equations represent? $-3x-y = -1$ $15x+5y = 5$
Explanation: Putting the first equation in $y = mx + b$ form gives: $-3x-y = -1$ $-y = 3x-1$ $y = -3x + 1$ Putting the second equation in $y = mx + b$ form gives: $15x+5y = 5$ $5y = -15x+5$ $y = -3x + 1$ The above equations turn into the same equation, so they represent equal lines.